Last visit was: 21 Apr 2026, 13:02 It is currently 21 Apr 2026, 13:02
Home
Messages
Tests
Schools
Events
Close
GMAT Club Daily Prep
Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track
Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
Go to My Error Log Learn more
Close
Request Expert Reply
Confirm Cancel
Back to Forum
Create Topic
705-805 (Hard)|   Assumption|      
User avatar
Frank28
User avatar
Joined: 31 May 2020
Last visit: 31 Aug 2020
Posts: 32
Own Kudos:
179
 [19]
Given Kudos: 33
GMAT 1: 760 Q51 V41
GMAT 1: 760 Q51 V41
Posts: 32
Kudos: 179
 [19]
Among people in Boravia who had a car accident while driving, 4 percen 06 Jul 2020, 05:05
2
Kudos
Add Kudos
16
Bookmarks
Bookmark this Post
00:00
Start Timer
Pause Timer
Resume Timer
Show Answer
Hide
Show
History
D
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!

Difficulty:

75% (hard)

Question Stats:

56% (02:14) correct 44% (02:26) wrong based on 563 sessions

History

Date
Time
Result
Not Attempted Yet
Among people in Boravia who had a car accident while driving, 4 percent of those under 50 years old were found to have prosinopsis, a currently untreatable eye disease that causes a gradual deterioration In peripheral vision. Yet the proportion of drivers under 50 who have been diagnosed with prosinopsis is only 2 percent in Boravia. Clearly, therefore, having the disease makes Boravian drivers under 50 significantly more likely to have a car accident.

Which of the following is an assumption on which the argument depends?

A. Among Boravians under 50 who had a car accident while driving, most of those who had prosinopsis had the disease in its late stages.
B. Prosinopsis is not more difficult to diagnose in a person under 50 than in someone older.
C. There is no way of correcting for deterioration in peripheral vision brought about by prosinopsis.
D. Boravian drivers under 50 who have prosinopsis have generally been diagnosed as having it.
E. Prosinopsis has no symptoms other than the deterioration of peripheral vision.

Source: topgmat
ShowHide Answer
Official Answer
D
Most Helpful Reply
User avatar
Frank28
User avatar
Joined: 31 May 2020
Last visit: 31 Aug 2020
Posts: 32
Own Kudos:
179
 [5]
Given Kudos: 33
GMAT 1: 760 Q51 V41
GMAT 1: 760 Q51 V41
Posts: 32
Kudos: 179
 [5]
Among people in Boravia who had a car accident while driving, 4 percen 09 Jul 2020, 05:34
5
Kudos
Add Kudos
Bookmarks
Bookmark this Post
ursk
why C is not the answer.Can anyone explain it
Show more


I would like to think about it this way.

The author says that

the percentage of people under 50 in accident who HAVE the disease is 4%
the percentage of all population under 50 who were DIAGNOSED to have the disease 2%
so it seems that HAVING the disease means more likely to have an accident.


What if like 50 out of 100 have the disease, only 2 out of 100 are diagnosed, and 4 out of 100 have the disease involved in accidents? then having the disease doesn't make people more likely to be involved in an accident. Therefore negating D can destroy the author's argument.


As for C, maybe it can/it can not be corrected. But here the author isn't discussing how the disease affects driving. Even if we can correct their visions, statistically it's still possible that people who have the disease are more likely to involve in accidents.
General Discussion
avatar
ursk
avatar
Joined: 05 Apr 2020
Last visit: 18 Nov 2020
Posts: 2
Own Kudos:
2
 [2]
Given Kudos: 10
Posts: 2
Kudos: 2
 [2]
Among people in Boravia who had a car accident while driving, 4 percen 09 Jul 2020, 05:18
Kudos
Add Kudos
Bookmarks
Bookmark this Post
why C is not the answer.Can anyone explain it
User avatar
thedarkwolf
User avatar
Joined: 30 Nov 2023
Last visit: 26 Jan 2025
Posts: 54
Own Kudos:
17
 [1]
Given Kudos: 20
Location: India
Concentration: General Management, Leadership
GMAT 1: 610 Q47 V27
GPA: 4
WE:Engineering (Manufacturing)
Products:
My Reviews
GMAT 1: 610 Q47 V27
Posts: 54
Kudos: 17
 [1]
Among people in Boravia who had a car accident while driving, 4 percen 06 Dec 2023, 10:39
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
The data says 4% of PPL , so the assumption is ppl have diagnosed
Thus D

Posted from my mobile device
User avatar
RiyaJ0032
User avatar
Joined: 13 Dec 2021
Last visit: 09 Feb 2026
Posts: 190
Own Kudos:
19
 [1]
Given Kudos: 53
Posts: 190
Kudos: 19
 [1]
Among people in Boravia who had a car accident while driving, 4 percen 21 Feb 2025, 01:47
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Hi ! DmitryFarber
MartyMurray

can you please provide an explanation for (D)

I did analyze the option but did not know how to further form an inference making (D) the ans

we are given that out of 100 people having a car accident
under 50 are (x), and above 50 are (100-x)
of which ( x/25 ) have prosinopsis
and this x/25 represent 2% of total drivers

so our total drivers are 2x

after this, how to conclude (D) to be the ans?

or if any expert could explain
Thank you so much
Frank28
Among people in Boravia who had a car accident while driving, 4 percent of those under 50 years old were found to have prosinopsis, a currently untreatable eye disease that causes a gradual deterioration In peripheral vision. Yet the proportion of drivers under 50 who have been diagnosed with prosinopsis is only 2 percent in Boravia. Clearly, therefore, having the disease makes Boravian drivers under 50 significantly more likely to have a car accident.

Which of the following is an assumption on which the argument depends?

A. Among Boravians under 50 who had a car accident while driving, most of those who had prosinopsis had the disease in its late stages.
B. Prosinopsis is not more difficult to diagnose in a person under 50 than in someone older.
C. There is no way of correcting for deterioration in peripheral vision brought about by prosinopsis.
D. Boravian drivers under 50 who have prosinopsis have generally been diagnosed as having it.
E. Prosinopsis has no symptoms other than the deterioration of peripheral vision.

Source: topgmat
Show more
User avatar
DmitryFarberMPrep
User avatar
Manhattan Prep Instructor
Joined: 22 Mar 2011
Last visit: 03 Mar 2026
Posts: 3,005
Own Kudos:
8,624
 [2]
Given Kudos: 57
Expert
Expert reply
GMAT Focus 1: 745 Q86 V90 DI85
Posts: 3,005
Kudos: 8,624
 [2]
Among people in Boravia who had a car accident while driving, 4 percen 22 Feb 2025, 23:53
2
Kudos
Add Kudos
Bookmarks
Bookmark this Post
It's an odd scenario, but what they're getting at is a sampling flaw. Apparently, we know for a fact that 4% of those who had an accident had this condition. But for the general population, we just know that 2% have been diagnosed. Maybe the issue is that when someone has an accident, we check for this condition. Maybe 4% or more of drivers do have it, but we don't find out until they get in an accident. In fact, the condition may be quite common and may not be affecting the likelihood of an accident at all.

Let's look at an analogous case. What if I have a theory that seeing cat videos cause illness? So when someone gets sick, I go through their browsing history for the prior week and--lo and behold--60% of them have watched a cat video. But when I ask random people if they've watched a cat video in the past week, only 10% say yes. Aha! Cat videos show up disproportionately among people who got sick, so they must be causing a problem, right? But wait! The groups aren't the same. The larger group was just self-reporting, whereas I was actually *checking* those who got sick. Maybe if I checked *everyone's* phone, I'd find that many people had actually watched a cat video, even if they didn't remember. I might find that this happened 60% of the time, meaning there was no correlation between the videos and illness. Or maybe I'd find cat videos 95% of the time, meaning that they are actually UNDERrepresented among sick people. Cat videos might actually be correlated with good health! (Whether we have causation or not is a whole other story.) Does that help?
RiyaJ0032
Hi ! DmitryFarber
MartyMurray

can you please provide an explanation for (D)

I did analyze the option but did not know how to further form an inference making (D) the ans

we are given that out of 100 people having a car accident
under 50 are (x), and above 50 are (100-x)
of which ( x/25 ) have prosinopsis
and this x/25 represent 2% of total drivers

so our total drivers are 2x

after this, how to conclude (D) to be the ans?

or if any expert could explain
Thank you so much
Frank28
Among people in Boravia who had a car accident while driving, 4 percent of those under 50 years old were found to have prosinopsis, a currently untreatable eye disease that causes a gradual deterioration In peripheral vision. Yet the proportion of drivers under 50 who have been diagnosed with prosinopsis is only 2 percent in Boravia. Clearly, therefore, having the disease makes Boravian drivers under 50 significantly more likely to have a car accident.

Which of the following is an assumption on which the argument depends?

A. Among Boravians under 50 who had a car accident while driving, most of those who had prosinopsis had the disease in its late stages.
B. Prosinopsis is not more difficult to diagnose in a person under 50 than in someone older.
C. There is no way of correcting for deterioration in peripheral vision brought about by prosinopsis.
D. Boravian drivers under 50 who have prosinopsis have generally been diagnosed as having it.
E. Prosinopsis has no symptoms other than the deterioration of peripheral vision.

Source: topgmat
Show more
User avatar
RiyaJ0032
User avatar
Joined: 13 Dec 2021
Last visit: 09 Feb 2026
Posts: 190
Own Kudos:
19
Given Kudos: 53
Posts: 190
Kudos: 19
Among people in Boravia who had a car accident while driving, 4 percen 23 Feb 2025, 00:55
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Hello!

I think I understand the sampling flaw you are getting at

of those who were ill, 60% were found to be watching cat videos
but general population, only 10% watch them. So we might conclude that watching cat videos causes illness

but what if amongst general population, 60% have watched the cat videos
so we might say there is no correlation

if I apply this same logic to option (D),

if the proportion of normal drivers with prosinopsis is just 2%
whereas the ones involved in accident is 4%
therefore, for the disease to cause the accident, it is assumed that these drivers have to be diagnosed with the disease?

If you please just could elaborate a little further,
this sampling flaw will be absolutely clear to me

Thank you so much!!
DmitryFarber
It's an odd scenario, but what they're getting at is a sampling flaw. Apparently, we know for a fact that 4% of those who had an accident had this condition. But for the general population, we just know that 2% have been diagnosed. Maybe the issue is that when someone has an accident, we check for this condition. Maybe 4% or more of drivers do have it, but we don't find out until they get in an accident. In fact, the condition may be quite common and may not be affecting the likelihood of an accident at all.

Let's look at an analogous case. What if I have a theory that seeing cat videos cause illness? So when someone gets sick, I go through their browsing history for the prior week and--lo and behold--60% of them have watched a cat video. But when I ask random people if they've watched a cat video in the past week, only 10% say yes. Aha! Cat videos show up disproportionately among people who got sick, so they must be causing a problem, right? But wait! The groups aren't the same. The larger group was just self-reporting, whereas I was actually *checking* those who got sick. Maybe if I checked *everyone's* phone, I'd find that many people had actually watched a cat video, even if they didn't remember. I might find that this happened 60% of the time, meaning there was no correlation between the videos and illness. Or maybe I'd find cat videos 95% of the time, meaning that they are actually UNDERrepresented among sick people. Cat videos might actually be correlated with good health! (Whether we have causation or not is a whole other story.) Does that help?
RiyaJ0032
Hi ! DmitryFarber
MartyMurray

can you please provide an explanation for (D)

I did analyze the option but did not know how to further form an inference making (D) the ans

we are given that out of 100 people having a car accident
under 50 are (x), and above 50 are (100-x)
of which ( x/25 ) have prosinopsis
and this x/25 represent 2% of total drivers

so our total drivers are 2x

after this, how to conclude (D) to be the ans?

or if any expert could explain
Thank you so much
Frank28
Among people in Boravia who had a car accident while driving, 4 percent of those under 50 years old were found to have prosinopsis, a currently untreatable eye disease that causes a gradual deterioration In peripheral vision. Yet the proportion of drivers under 50 who have been diagnosed with prosinopsis is only 2 percent in Boravia. Clearly, therefore, having the disease makes Boravian drivers under 50 significantly more likely to have a car accident.

Which of the following is an assumption on which the argument depends?

A. Among Boravians under 50 who had a car accident while driving, most of those who had prosinopsis had the disease in its late stages.
B. Prosinopsis is not more difficult to diagnose in a person under 50 than in someone older.
C. There is no way of correcting for deterioration in peripheral vision brought about by prosinopsis.
D. Boravian drivers under 50 who have prosinopsis have generally been diagnosed as having it.
E. Prosinopsis has no symptoms other than the deterioration of peripheral vision.

Source: topgmat
Show more
User avatar
DmitryFarberMPrep
User avatar
Manhattan Prep Instructor
Joined: 22 Mar 2011
Last visit: 03 Mar 2026
Posts: 3,005
Own Kudos:
8,624
 [2]
Given Kudos: 57
Expert
Expert reply
GMAT Focus 1: 745 Q86 V90 DI85
Posts: 3,005
Kudos: 8,624
 [2]
Among people in Boravia who had a car accident while driving, 4 percen 23 Feb 2025, 14:38
2
Kudos
Add Kudos
Bookmarks
Bookmark this Post
You've got it. If we actually KNEW that only 2% of drivers had prosinopsis, the argument would make more sense. But since we only know that 2% have been diagnosed with it--the actual rate may be higher. Meanwhile, we know the real rate for those who've been in accidents--it's 4%. So the argument relies on the assumption that there aren't many people out there who DO have prosinopsis but haven't been diagnosed.

This fits a common pattern in assumptions: fixing term mismatches. The premises are about "% that have P" and "% diagnosed with P." Those aren't necessarily the same thing, so D fixes the mismatch by saying that in this case, they are roughly the same.
RiyaJ0032
Hello!

I think I understand the sampling flaw you are getting at

of those who were ill, 60% were found to be watching cat videos
but general population, only 10% watch them. So we might conclude that watching cat videos causes illness

but what if amongst general population, 60% have watched the cat videos
so we might say there is no correlation

if I apply this same logic to option (D),

if the proportion of normal drivers with prosinopsis is just 2%
whereas the ones involved in accident is 4%
therefore, for the disease to cause the accident, it is assumed that these drivers have to be diagnosed with the disease?

If you please just could elaborate a little further,
this sampling flaw will be absolutely clear to me

Thank you so much!!
DmitryFarber
It's an odd scenario, but what they're getting at is a sampling flaw. Apparently, we know for a fact that 4% of those who had an accident had this condition. But for the general population, we just know that 2% have been diagnosed. Maybe the issue is that when someone has an accident, we check for this condition. Maybe 4% or more of drivers do have it, but we don't find out until they get in an accident. In fact, the condition may be quite common and may not be affecting the likelihood of an accident at all.

Let's look at an analogous case. What if I have a theory that seeing cat videos cause illness? So when someone gets sick, I go through their browsing history for the prior week and--lo and behold--60% of them have watched a cat video. But when I ask random people if they've watched a cat video in the past week, only 10% say yes. Aha! Cat videos show up disproportionately among people who got sick, so they must be causing a problem, right? But wait! The groups aren't the same. The larger group was just self-reporting, whereas I was actually *checking* those who got sick. Maybe if I checked *everyone's* phone, I'd find that many people had actually watched a cat video, even if they didn't remember. I might find that this happened 60% of the time, meaning there was no correlation between the videos and illness. Or maybe I'd find cat videos 95% of the time, meaning that they are actually UNDERrepresented among sick people. Cat videos might actually be correlated with good health! (Whether we have causation or not is a whole other story.) Does that help?
Show more
User avatar
MartyMurray
User avatar
Joined: 11 Aug 2023
Last visit: 21 Apr 2026
Posts: 1,830
Own Kudos:
7,081
Given Kudos: 209
GMAT 1: 800 Q51 V51
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
GMAT 1: 800 Q51 V51
Posts: 1,830
Kudos: 7,081
Among people in Boravia who had a car accident while driving, 4 percen 25 Feb 2025, 20:19
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Here's the original version of that question, which is from the official practice tests.

https://gmatclub.com/forum/among-people ... 27112.html
Moderators:
GMATNinja
GMAT Club Verbal Expert
7391 posts
AbhishekP220108
495 posts
bhanu29
358 posts